Right now in Texas, we're having freezing nights and cold, rainy days. December is anybody's guess with the weird weather we've been getting the past couple of years. My wife and I go to the Florida Keys every spring, where warm, stable weather is more of a guarantee (such as weather ever can be). I'm between Houston and San Antonio and the cold fronts make it down to Matagorda. But if the weather's nice, Texas is a great place for early winter outdoors activity! Down the coast by Corpus Christi and further south should be nicer all winter.